Introductory material
Reading edition
BARIUM, A CAUSE OF THE LOCO-WEED DISEASE.
GEOGRAPHICAL DISTRIBUTION OF THE LOCO-WEED DISEASE AND ALLIED CONDITIONS.
In our Western States there is a marked annual loss of stock due to various causes. Some of these animals die in a condition known as ‘locoed,’ a term derived from the Spanish word “loco,” meaning foolish or crazy.
This disorder extends from Montana to Texas and Mexico, and from Kansas and Nebraska to California.[1]
In 1898 the United States Department of Agriculture sent out, under the immediate direction of Mr. V. K. Chesnut, a request for information concerning the ravages of the loco disease. It was found that in the ten States of California, Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, Texas, and Wyoming the loss in 1898 was $144,850. Of this amount, $117,300 was attributed to Colorado alone; in fact, the disorder spread so that this State expended more than $200,000 in two years and over $425,000 in a period of nine years in attempts to eradicate the loco plants, the supposed cause of the trouble.[2]
The loss in one area of 35 by 120 miles in southwestern Kansas amounted to 25,000 cattle in 1883.[3] This loss in stock has been so great that the raising of horses has of necessity been abandoned in certain areas on account of the prevalence of these loco weeds.
It is difficult to obtain accurate data, as the ranchmen believe that any information as to the prevalence of the disorder would interfere with the value of their stock.[4]
Dr. James Fletcher, of the Central Experimental Farm, Ottawa, Canada, testified before the Select Standing Committee on Agriculture and Colonization that he had never seen a case in the North-west of a Canadian bred animal being locoed, although the loco plants were prevalent. He explained this absence of loco disease by the abundance of grass on the range, because of which the animals do not acquire the habit of eating loco plants.[5] Cases have been reported, however, in Manitoba.[6]
FOOTNOTES:
PLANTS ASSOCIATED WITH THE LOCOED CONDITION.
The condition known as “locoed” is popularly believed to be due to eating various plants, especially the members of the Astragalus and Aragallus genera of the Leguminosæ, or pea family, but particularly to Astragalus mollissimus and Aragallus lamberti. These plants have therefore received the name “loco plants,”[7] or crazy weed. But others, as Astragalus mortoni,[8] A. hornii, A. lentiginosus, A. pattersoni,[9] A. nuttallianus, A. missouriensis, A. lotifloras, A. bisulcatus, A. haydenianus,[10] A. tridactylicus,[11] Crotalaria sagittalis, Lotus americanus,[12] Sophora sericea, Caprioides aureum, Aragallus deflexa,[13] A. campestris,[14] A. lagopus,[15] Malvastrum coccineum, Amaranthus graecizans, and Rhamnus lanceolata, are considered by some as loco plants.[16] In other places Stipa vaseyi, Leucocrinum montanum, Fritillaria pudica, Zygadenus elegans,[17] and even species of Delphinium are considered loco plants, so widely has this name been used.
In Mexico the term “locoed” embraces a condition due to the action of Cannabis sativa and various members of the nightshade family. This term has been much abused and has been made to embrace many groups of symptoms. In fact, if an animal dies while showing more or less stupor it is said to be locoed.[18] The early Spanish settlers seemed to be unfamiliar with the disease, or at least of any causative relation between the plant and the disease. The Spanish name for Astragalus mollissimus was “Garbanzillo,” from its resemblance to Garbanzo (Cicer arietinum), which is used in Spain as a food.[19] The term as applied to this condition seems to be of comparatively recent origin.[20]
A somewhat similar condition to the loco in stock is sometimes attributed by the ranchmen of our Western States to eating various sages.[21] In Texas the loco disease is known as “grass staggers.”[22]
Hayes[23] has described as follows a condition known as grass staggers, which apparently has little resemblance to loco and is supposed to be due to eating overripe grass, especially rye.
The symptoms, generally, take two or three days to become developed. The animal gradually becomes more or less unconscious and paralyzed and staggers if forced to walk. Although he may have great difficulty in keeping on his legs, he is extremely averse from going down and leans for support against any convenient object. He breathes in a snoring manner. The mucous membranes are tinged with yellow. Convulsions, or spasms, like those of tetanus, may come on.
Recovery may be expected in cases which are not marked by extreme symptoms.
If animals are not regularly salted, they visit salt deposits and eat the alkalis. This some sheepmen believe to be the cause of the locoed condition, but this is disproved by the occurrence of locoed animals in ranges without salt. Others modify this view by claiming that the vitiation in taste from eating these alkalis leads to a desire for the loco weeds and thus to the locoed condition.[24]
FOOTNOTES:
CLINICAL SYMPTOMS OF LOCOED ANIMALS AS DESCRIBED IN LITERATURE.
The animals usually affected are sheep, horses, cattle, mules,[25] donkeys,[26] and goats. It is claimed that practically all herbivorous animals are liable to the disease, even antelopes being affected.[27] Hogs are said to be unaffected,[28] but definite information is lacking. Cows seem to be less sensitive to this form of intoxication.[29] The condition is usually a chronic one, although acute cases are said to occur at times. The symptoms consist of digestive disturbances, associated with emaciation and various symptoms suggesting lesions in the nervous system, central or peripheral. The animals lose their appetite from the first, begin to emaciate, and show symptoms of malnutrition and starvation. The head trembles, the gait becomes feeble and uncertain, the eyes become sunken and have a “flat, glassy look.”[30] There is a general sluggishness, muscular incoordination, and difficulty in motion; finally all control of the limbs is lost and the animal is unable to stand; the coat becomes rough and loses its luster, and, in fact, all the typical symptoms of starvation appear. In some cases diarrhea is also present.
All of Nockolds’s animals, however, were constipated and the stools were covered with mucus.[31] The dependent portions of the body may swell, simply as an expression of the anæmia.[32] Sometimes there are symptoms indicating acute pain,[33] the animals running about as if affected with colic. They may belch and their abdomens swell. Some claim that the animals are markedly salivated so that the saliva trickles from their mouths. In other cases the mouth may be dry.[34] The eyes may be rolled up so that the whites alone show. In some cases the pupil has been noted to be dilated, as in atropine poisoning,[35] but Wilcox states that they are contracted as after the use of eserine.[36] The temperature of the animal falls from 1/2 degree to 1-1/2 degrees F. below normal.[37] Tetanic symptoms may occur,[38] or the muscles of the mouth and tongue becoming paralyzed may interfere with mastication. When water is offered to the animal, it gazes stupidly at it and may not drink for days. One of the symptoms noted is the loss of power to back properly.[39] Cows during the first two or three months of gestation are almost sure to abort.[40] This is claimed by Knowles, however, to be due to malnutrition. As a result of these observations, suggesting some uterine action, the drug has been proposed as an emmenagogue.[41]
The psychical symptoms are shown by errors of judgment. The animal becomes dull and spiritless and wanders about half dazed. The mental dullness passes into stupor. This dull, stupid condition has been compared to intoxication with opium. If the locoed horse is led across a stick lying on the ground he often jumps high as if it were a great obstacle. The animal may now have maniacal attacks, during which he rears and may fall backward,[42] and makes unreasonable jumps and other unexpected movements, thus rendering himself dangerous to man.[43] Other symptoms due to disturbances of the central nervous system are hallucinations of various sorts. Though the optic nerve itself is apparently not affected, the animal will stare at an object for a long time without any apparent comprehension of its nature. This disturbance in the visual function McCullaugh claims to be one of the first symptoms of this disease. The animal seems to lose all idea of distance, as he will butt against an obstruction as if oblivious of its presence. Any sudden or violent motion made before him may cause him to fall. According to some, the animal loses the sense which guides him in finding water. A cow may fail to recognize her calf.[44] There is more or less loss of control of the limbs[45] and tremors;[46] the feet are lifted abnormally high when trotting, and, if crowded, the animal falls headlong and will jump over little hollows as if they were wide ditches.[47] The horse may shy without apparent cause and kick at imaginary objects,[48] and, in fact, the reasoning powers seem to be lost. These attacks are brought on by sudden excitement or when crossing water.[49] There may be cutaneous hyperæsthesia.
The animals may remain with the herd, but they often wander away. Stalker records the following observations:
I have seen a single animal miles away from any other individual of the herd, carefully searching as if for some lost object, and when a loco plant is found he would devour every morsel of it with the greatest relish. As soon as one plant was eaten he would immediately go in search of more, apparently oblivious to everything but the intoxication afforded by his one favorite article of food.[50]
All of Nockolds’s animals which were locoed were mares more than 6 years of age.[51]
According to Stalker there is a passive type in which the animal shows symptoms only on being disturbed; the animal then becomes unmanageable. This happens even with old, well-broken saddle horses.[52]
There are few published reports as to the symptoms occurring in sheep which are locoed. Stalker[53] says sheep “become loco-eaters, grow stupid, emaciated, and eventually die.” One of the few descriptions of the symptoms is that of Ruedi,[54] in which he claims that the symptoms in sheep are those comparable to the symptoms of cerebro-spinal meningitis except that there is an absence of fever. Ruedi speaks of sheep “lying flat on the ground, not able to stand, and not able even to lift their heads to drink the offered water; the head and the vertebra in opisthotonus position; the four legs stretched out and stiff; breathing was stertorous, pulse slow, abdomen much distended, diarrhea present. * * * The heart * * * was very slow and insufficient.” The teeth (in sheep) may blacken and fall out.[55]
It is mainly the young animals, such as lambs and colts, that are affected, probably due to the fact that their attention is more easily directed to the flower of the loco[56] plants. It is claimed (on slight evidence) that men have become locoed. The symptoms in them are nausea and headache.[57]
Schuchardt[58] has called attention to the resemblance of the symptoms in locoed animals to those which occur in so-called lathyrism, but most observers in this country have especially marked the resemblance of the symptoms to those induced by the habitual use of narcotic drugs.[59]
As a rule the loco plants are refused by animals save when there is lack of other food, although at times animals have shown the keenest relish for these plants, rejected all other forage, and devoted their whole attention to searching for the loco plants.[60]
Stalker says that animals not too long addicted to the use of these plants, if confined, soon lose their taste for them (after two or three months),[61] although old loco eaters do not readily lose the habit. Stalker also says that “it is to be presumed that the plant is possessed of some toxic property that has a specific effect on the nervous centers, and that these effects have a marked tendency to remain permanent.”[62]
The fundamental character of the disorder seems to be a progressing anæmia. The interpretation of psychical symptoms in herbivora, and especially on the range, must often be fallacious.
FOOTNOTES:
CONDITIONS SIMILAR TO LOCO-WEED POISONING IN OTHER PARTS OF THE WORLD.
According to Maiden[63] a condition similar to loco is met with among animals in Australia and is there believed to be due to eating various species of Swainsona.[64] As Maiden says, “Its effect on sheep is well known; they separate from the flock, wander about listlessly, and are known to the shepherds as ‘pea-eaters’ or ‘indigo-eaters.’ When once a sheep takes to eating this plant it seldom or never fattens, and may be said to be lost to its owner.” Horses, after eating this herb, “were exceptionally difficult to catch, and it was observed how strange they appeared. Their eyes were staring out of their heads and they were prancing against trees and stumps. The second day two out of nine died, and five others had to be left at the camp.”
Martin[65] experimentally studied these cases of intoxication and sums up his work as follows:
1. That one can by feeding sheep upon Darling pea reproduce all the symptoms which are attributed by pastoralists to this cause. Briefly stated these symptoms are: Stupidity, loss of alertness and an agonized expression, followed by stiffness and slight staggering and frequently trembling of the head or limbs. Later, clumsiness and unsteadiness ensue, which slowly advance until the animal often falls down. In this stage, the action of the animal in running over small obstacles is characteristic. It jumps over a twig as if it were a foot in height. When first it commences to tumble about, it is able more or less readily to regain its feet, but in the advanced stage of the disease this is impossible and, after exhausting itself in efforts to do so, it remains lying down until it dies. During the whole time the sheep become progressively more bloodless, and in advanced cases the blood when shed appears to the naked eye lighter in color. It contains fewer red blood-cells (about two-thirds to one-half the usual number). (The corpuscles were estimated in several cases by means of a hæmocytometer.) All these symptoms are much aggravated by driving. Thus, an animal in which the symptoms are little marked may exhibit them in a striking degree after being driven. In addition to the above the teeth (especially in young sheep) frequently become loose, and consequently displaced or even dislodged.
2. That the time which elapses before the onset of definite symptoms is three to four weeks in sheep of 2 to 3 years old. (It is probable, however, that with younger animals the time is shorter.)
3. That under the conditions of the experiment, the animals survived about three months. They lived, however, an invalid’s life. Everything was brought to them, and it is improbable that if feeding exclusively upon the pea, and left to shift for themselves in the paddocks, they would survive more than two months.
4. That if a sheep be returned to proper fodder after one month to six weeks feeding upon the pea, and before the symptoms are fully established, it may recover completely.
5. That when once the paralytic symptoms are established it will not recover; but if returned to proper food, will remain in much the same condition, becoming neither better nor worse.
6. That Darling pea contains a very fair amount of nourishing material so that animals may, provided they eat it readily, retain their condition on it for some weeks, until the poisonous principle contained has had time to exert its effects.
These plants, if fed with other herbage, do not seem to be injurious and apparently lose their harmful action upon being cultivated.[66] As long as salt is properly fed the animals will not eat this plant[67] and are said to suffer no effects from it. Physiological study has shown the presence of a body with marked sudorific power which causes rapid emaciation in frogs.[68]
It has been claimed that these symptoms are due to the presence of a narcotic poison in the plant.[69] Post-mortem examinations were negative save for the presence of a peripheral neuritis.[70]
FOOTNOTES:
PATHOLOGICAL CONDITIONS IN LOCOED ANIMALS AS DESCRIBED ON THE RANGE.
The pathological features as described by previous writers are a softening and ulceration of the stomach walls[71] and a degeneration of the walls of the intestines with or without perforations. The peritoneum may be found inflamed.[72] The peritoneum and omentum in one case (cow), reported by Sayre, were covered with small nodules. These were probably tubercular in origin. The colon in one horse was found enormously distended, while the cœcum and small intestines were normal,[73] save that the walls appeared thin.
Ulcers have been found at times in the kidneys, but were probably secondary in origin, as other cases are reported with normal kidneys. Faville has found in some cases amyloid degeneration. The pancreas and spleen are reported normal. The abdominal cavity may contain a slight effusion.[74] The liver has been found cirrhotic, and at times shows tubercular lesions of a secondary nature. The inner coat of the bladder has been found softened, and in sheep the bladder may be markedly distended at the autopsy. The cerebral membranes are congested and perhaps adherent,[75] and there may be blood clots over the longitudinal sinus or at the base of the brain. Effusions have been especially noted around the medulla. The arachnoid has also shown slight congestion, and in other cases the membranes showed a slight thickening. The middle ventricle was found filled with yellow serum, while the fourth ventricle contained a hemorrhagic effusion,[76] and the base of the brain was covered by a clot. The hemorrhage may become organized and the brain be held to the membranes by tough organized fibers. In many cases serous effusion is present in the lateral ventricles. The arachnoid space is also in some cases similarly filled. Microscopic examination of the brain in the case of a steer showed atrophy of Purkinjie’s cells.[77]
In sheep the post-mortem examination showed paleness, anæmia of the muscles, and great distention of the abdomen. The intestines were found filled with gases, and the mesenteric blood vessels filled with blood. No peritonitis, or ascites, or ecchymoses in the mucous membranes were noted in the autopsies made on sheep by Ruedi. The liver has been seen enlarged. In sheep the brain was anæmic. Microscopically the brain showed atrophy and the Purkinjie’s cells disappeared or their processes atrophied. In these sheep the brain was so anæmic that the distinction between the gray and the white matter was hard to define.[78] The membranes of the cord have been found inflamed and adherent, but the spinal cord was usually normal.[79] In some cases, however, the spinal cord has been found softened[80] and œdematous. The arteries of the limbs were gorged with blood,[81] and at the same time there was a collection of serum in the abdominal cavity. Death is thought to be due to starvation.[82] In other words, the pathological condition, according to published accounts, shows little that is characteristic save some action on the gastro-intestinal tract.
FOOTNOTES:
HISTORICAL SKETCH OF LOCO INVESTIGATIONS FROM A PHARMACOLOGICAL STANDPOINT.
During the western immigration of 1849 the Indians along the Missouri River described to the immigrants a plant (Astragalus mollissimus) producing death in horses and cattle, which was preceded by various forms of excitement.[83]
The attention of the United States Department of Agriculture was first called to the toxic action of the loco plants in 1873, when specimens of the plants, which were identified as Astragalus hornii and A. lentiginosus,[84] were sent from California by Mr. O. B. Ormsby, with the statement that they were poisonous to stock, especially to horses. Mrs. J. S. Whipple also corroborated this information. The botanist of the Department, Dr. George Vasey,[85] published a note and requested further information concerning the plants. These notes were enlarged by a similar contribution by Dr. P. Moffat on Aragallus lamberti.[86] The following year Vasey reported with more fullness, and his description of the action of the plants is substantially what we find in most of the books of to-day.
In 1876 Lemmon[87] noted that Astragalus mortoni was “a deadly sheep poison.” At the same time Rothrock,[88] botanist of the United States Geographical Survey under Lieutenant Wheeler, described these plants, and Kellogg,[89] a botanist in California, reported that Astragalus menziesii was causing great losses in horses, sheep, and cattle and claimed that the stockmen had been familiar with this disorder for at least ten or fifteen years. This report of Kellogg was followed by that of Rothrock[90] in 1877.
In 1876 a specimen of Aragallus lamberti was sent from Colorado to Professor Prescott, of the University of Michigan, under the name of “crazy weed,” with the statement that it was poisonous to horses and cattle and that, while the Mexicans often used it in making beer, it sometimes caused symptoms in men. His pupil, Miss Watson, undertook a study of its chemical properties. She failed to isolate any pure chemical compound, but claimed that in the root there was a body giving alkaloidal reactions and that there was also a resinous body present. Another of his pupils, W. R. Birdsall, took the ground-up root himself in doses of 20 grains at various intervals for several days and later 40-grain doses in one and a half hours, but without experiencing any marked symptoms except colicky pains. A kitten also was given about one and a half ounces of the fluid extract without effect. Prescott[91] sums up by saying that “it would seem that the dried ground root possesses no poisonous properties.” The work of Miss Watson was considered of sufficient importance to be abstracted in the Annual Report of the Commissioner of Agriculture for 1878 (1879), page 134.
Gradually the Department of Agriculture became more and more interested in this subject, and Peter Collier, chief chemist, in 1878, examined the roots and leaves of Aragallus lamberti for alkaloids, but found none.[92]
In 1880 Peter Collier published a proximate analysis of Astragalus mollissimus made by Francis A. Wentz, of Kansas. His investigations showed it to have an ash content of 6.76 per cent, while the Aragallus lamberti, analyzed by L. F. Dyrenforth, of Chicago, showed an ash content of 4.32 per cent. Collier[93] sums up by saying:
From the additional work done at this Department it seems probable that the deleterious effects observed from animals eating this plant may be due principally to the fact that the sweet taste causes cattle to reject more nutritious food and strive to subsist upon the Oxytropis only. This plant is mechanically a very unfit substance for food, being of a tough, fibrous, and indigestible character. It is possible that, when the animal becomes somewhat enfeebled by lack of proper nourishment, the small amount of alkaloid may have a direct poisonous action. Again, it seems probable that the plant may contain much larger proportions of alkaloid at certain stages in its development than at others, or the seeds may prove to be the most injurious portion.
The departmental work was continued by further short notices by Vasey[94] in 1884, 1886, and 1887, and by the report of Stalker in 1887. This report by Stalker is still the best description on the clinical side of the question.
Rothrock,[95] meeting the loco plants in his survey work, describes their effects on animals as follows:
Certain it is, however, that, once commenced, they continue it, passing through temporary intoxication to a complete nervous and muscular wreck in the later stages, when it has developed into a fully marked disease which terminates in death from starvation or inability to digest a more nourishing food. The animal toward the last becomes stupid or wild, or even vicious, or, again, acting as though attacked with “blind staggers.”
Under the name of Crotalaria, H. Gibbons,[96] in 1879, refers to a plant growing in California which it was claimed was producing characteristic symptoms of poisoning in horses and sheep. This plant Professor Maisch afterwards identified as Aragallus lamberti.
Dr. Isaac Ott[97] undertook the physiological study of the question and used an alcoholic extract of Astragalus mollissimus. He found from its action on frogs, rabbits, and cats that the plant had decided physiological action, as follows:
(1) It decreases the irritability of the motor nerves.
(2) Greatly affects the sensory ganglia of the central nervous system, preventing them from readily receiving impressions.
(3) Has a spinal tetanic action.
(4) Kills mainly by arrest of the heart.
(5) Increases the salivary secretion.
(6) Has a stupefying action on the brain.
(7) Reduces the cardiac force and frequency.
(8) Temporarily increases arterial tension, but finally decreases it.
(9) It greatly dilates the pupil.
Doctor Stockman, in England, about this time tried the action of the aqueous and alcoholic extracts of the dried Astragalus mollissimus sent from Texas. He experimented with frogs and rabbits in increasing doses, but without result.[98]
In 1888 Hill reported that a species of Astragalus was acting detrimentally on cattle, goats, and sheep in Cyprus and that these animals fell down as if intoxicated, and also that the natives in time of great drought feed their cattle with this plant mixed with straw, but that they were always made sick until they became used to it.
In 1885 Professor Sayre, of the University of Kansas, undertook the investigation of the loco question. His first report was made in the Transactions of the Kansas Academy of Sciences for 1885, and his reports have been continued at various periods up to 1904. The results of his experiments on various animals—dogs, cats, and frogs[99]—have been entirely negative. He administered alcoholic preparations to himself and took them until they became too nauseous to continue, and found they produced absolutely no symptoms besides the nausea. He suggests, however, that if the plant really is poisonous it is due to its fine hairs, which might mechanically cause death. Sayre has stated that he has sent thousands of pounds of the dried loco plants to various investigators in America and Europe, but all reports were negative as to pharmacological activity. He has, however, done some work on the pure chemistry of the plant and found that the plant contained 10 per cent of moisture and yielded 12.01 per cent of ash. Of this ash, 25 per cent was soluble in water, while 50.6 per cent was soluble in HCl. The insoluble portion consisted largely of silica. He found CaO, K2O, MgO, Al2O3, and Fe2O3, with the acid radicals SO3, Cl, P2O5, CO2, and SiO2.[100] Although Sayre claims that the plant is physiologically inactive, he tried by chemical means to isolate a physiologically active body and, naturally enough under the circumstances, failed to find one. He claims that while the plant might give alkaloid reactions, he was unable to isolate this body in a pure state, and that alfalfa reacted similarly.
The investigation on animals was continued by Kennedy.[101] He administered an infusion of 1/2 ounce of green Astragalus mollissimus to a fasting dog weighing 23 pounds, but there were no symptoms after 12 hours. A decoction of 1 ounce of the green plant and one of 4 ounces of the dried plant were likewise without action. Extracts with hydrochloric acid were also inactive. When 400 grams of the dried and powdered plant were fed in substance the result was merely to increase the appetite. The organic acid obtained from 4 ounces of the plant was also found to be inert.
Kennedy did not state in what season the plant was collected and from what locality it was obtained, but says simply that the plant extract was inactive to a dog, a carnivorous animal, and that therefore the plant is nonpoisonous. He adds that death might be due to the tough fibers and indigestible character of the plant. He overlooks, however, the fact that the plant might vary in its toxicity, and he infers from the experiments on carnivorous animals that these results would hold good for herbivora, yet he does not claim that carnivora become locoed in nature.
Kennedy found that the plant lost 80 per cent in weight on drying and that the water extract which represented 30.6 per cent of the powdered and dried plant contained magnesium sulphate and sodium chlorid, tannic acid, gum, coloring matter, an extractive, and a “peculiar organic acid.” The ashed plant yielded 20 per cent of ash, consisting of magnesium sulphate, sodium chlorid, alumina, silica, and a trace of iron. “The abundant precipitate produced by the alkaline hydrates, potassium, sodium, and ammonium was found to consist of magnesium hydrate, an abundance of this base being present in the plant.” Kennedy also obtained alkaloidal reactions, but failed to isolate the body giving these reactions.
In 1889 the investigations were greatly stimulated by the report of Doctor Day,[102] then of the University of Michigan. She claimed that she was able to produce marked physiological symptoms, using both Astragalus mollissimus and Aragallus lamberti in her work. She administered daily 60 to 70 c.c. of a decoction[103] of the plants to kittens, together with abundant milk and other food. She states that in two days—
The kittens became less active, the coat grew rough, appetite for ordinary food diminished and fondness for the “loco” increased, diarrhea came on, and retching and vomiting occasionally occurred. The expression became peculiar and characteristic. Emaciation and the above symptoms progressively increased until the eighteenth day, when periods of convulsive excitement supervened. At times the convulsions were tetanic in character; frothing at the mouth and throwing the head backward as in opisthotonus were marked. At other times the kitten would stand on its hind legs and strike the air with its forepaws, then fall backward and throw itself from side to side. These periods of excitement were followed by perfect quiet, the only apparent sign of life being the respiratory movements. After a short interval of quiet the convulsive movements would recur. These alternate periods of excitement and quiet lasted thirty-six hours, when the posterior extremities became paralyzed, and the kitten died about two hours afterward. There was no apparent loss of consciousness before death.
The post-mortem examination revealed the presence of ulcers in the stomach and duodenum. Some of the ulcers had nearly perforated the walls of the stomach and duodenum. The heart was in diastole; brain and myel appeared normal. As might be expected from the emaciated condition, the entire body was anæmic.
In a second case 60 to 70 cubic centimeters of a more concentrated decoction were fed daily, with other food as before, to a vigorous adult cat. The symptoms of inactivity, loss of appetite, rough coat, diarrhea, and the peculiar expression of countenance were as in the first case. By the twelfth day the cat was wasted almost to a skeleton, and was correspondingly weak. Paralysis of the hind limbs came on, and the cat died on the thirteenth day. There were no periods of excitement in this case.
These cats developed a craving for the decoction and “would beg for it as an ordinary kitten does for milk, and when supplied would lie down contented.”
Doctor Day made controls with healthy animals under the same conditions, with the exception that they received no loco plant. She also fed a young wild jack rabbit on milk and grass for a few days and then substituted fresh loco plants for grass.
At first the “loco” was refused, but after two or three days the “loco” was eaten with as much relish as the grass had been. After ten days of the milk and “loco” diet the rabbit was found dead, with the head thrown back and the stomach ruptured.
Subcutaneous injections of the concentrated decoction caused nervous twitchings in frogs and kittens, and if large amounts were used death followed in from one to two hours from paralysis of the heart. The same symptoms were produced in frogs by the injection of an alcoholic extract of the residue left after the evaporation to dryness of the decoction.
In other words, Doctor Day was able to produce a chronic form of loco poisoning with the characteristic symptoms so often described save in the occurrence of diarrhea. Diarrhea is not usually noted on the range. Sayre had already reported an ulcerated condition of the intestines of a locoed cow similar to that described by Doctor Day as occurring in cats. Doctor Day urged that the reason previous experimenters failed to produce symptoms was that they had used too small an amount of the plant and that by systematic feeding to healthy cats cases of loco disease may be produced.
Storke states that “Dr. V. C. Vaughan, of the University of Michigan, has since fully corroborated Dr. Day’s views.”[104]
In her experiments Doctor Day used the leaves, roots, and stems of the plants gathered in September. She believed that the greatest amount of poison is present in autumn and winter. She later undertook the isolation of the active principle, and proceeded as follows:[105]
The roots, stems, and leaves were boiled ten hours, strained, and the decoction concentrated to a sirup, poured, while hot, into a hot flask, corked and set away. At the end of ten days the sirup had separated into two layers—the upper a blackish liquid, the lower a brownish sediment. The liquid was poured into a flask and covered with six times its volume of very dilute alcohol, 30 per cent (the sediment also was washed with dilute alcohol, to insure a complete removal of the liquid), corked, and let stand three days; agitated occasionally, then filtered, and the filtrate slowly evaporated in the air, when crystals were formed. It was found important not to hurry the evaporation, for when this took place too rapidly the crystals did not form.
These crystals are microscopic in size, blue-white in color, and of a variety of forms. The most characteristic are slender and pointed, arranged in rosettes or grouped in various ways. They are soluble in distilled water and very dilute alcohol, very sparingly soluble in strong alcohol, not soluble in chloroform or ether.
The evaporated mass containing the crystals, when dissolved in distilled water, is slightly acid in reaction. A small amount of this fed to a kitten produced the train of characteristic toxic symptoms—sleepiness, loss of appetite, retching, and diarrhea—that is produced by quite large amounts of the decoction.
The crystals Sayre[106] claims to have already seen. He says that they gave no precipitate with Mayer’s reagent, platinum chlorid, or with ammonia, but that barium chlorid and ammonium oxalate gave a precipitate, and he believes that they were in reality an inorganic combination of calcium, so that while Doctor Day may have obtained an extract which produced characteristic symptoms she certainly has not isolated any pure active principle. Later she admitted that it was not possible “to make positive statements as to the chemical character of the active principle.”[107]
In 1884 there was a fatal outbreak of a disorder in horses in portions of the Missouri Valley in Iowa, Nebraska, and Dakota. This was almost uniformly fatal in a few weeks or months. The animals lost strength and became emaciated, although they were kept in pasture where there was abundant grass. There was marked stupor, the animals falling asleep while eating, and they “would remain standing for a whole week, sleeping much of the time, with the head resting upon some object.” The post-mortem examination showed that “in every instance there was marked hemorrhagic effusion into the fourth ventricle, the liver and spleen were abnormally dense, the walls of the intestines were almost destitute of blood, and the stomach enormously distended with undigested food.” The post-mortem find and clinical symptoms suggested to Stalker[108] that this disorder was due to some plant analogous to Astragalus mollissimus. He found abundant in these regions Crotalaria sagittalis, or rattle-box, one of the so-called loco weeds, and by the administration per os to a young horse of an infusion of 15 pounds of the plant, given in two days, produced the clinical symptoms and the post-mortem condition of the brain which he previously observed on the range.
Power and Cambier[109] undertook the chemical study and the isolation of the active principle of this plant, together with that of Astragalus mollissimus. They found that the Astragalus mollissimus if distilled with water yielded a distillate which possessed a peculiar odor, which they thought due to a trace of volatile oil. On distilling with alkali they obtained ammonia and a trace of trimethylamine. In the case of Crotalaria only ammonia was found.[110] They argued that because trimethylamine was not obtained in this case choline was not present. On distilling the Astragalus mollissimus with acidulated water (H2SO4) the distillate was found to contain acetic acid—settling the nature of the “peculiar organic acid” described by Kennedy. From this plant they obtained a resin or mixture of resinous bodies by extracting the plant with alcohol, and after concentration precipitating with acid water. These resins in doses of from 2 to 5 grains failed to produce any symptoms in kittens.
An albuminoid which was obtained by precipitating a concentrated aqueous extract of Astragalus mollissimus by means of alcohol likewise was found to be inactive to a kitten in doses corresponding to 50 grams of the crude plant. A globulin which was isolated by precipitation from a 10 per cent sodium chlorid solution proved also to be inactive in doses of 0.2 gram. They then extracted 3 kilograms of these plants with 1/2 per cent sulphuric acid, and after evaporation to a thick gum the mass was extracted with strong alcohol, the alcoholic solution was evaporated, and the alcoholic residue taken up in water and precipitated by neutral and basic lead acetates, and after removing the lead with sulphureted hydrogen the filtrate gave precipitates with various alkaloidal reagents. The sirupy residue which they obtained from Astragalus mollissimus by decomposing the precipitate with Mayer’s solution administered to kittens in doses of 0.1 gram produced merely frothing at the mouth with profuse flow of saliva, but the animals soon recovered. The presence of a large amount of calcium was shown but not estimated quantitatively.
Power and Cambier summed up their conclusions by stating that both the Astragalus and the Crotalaria contain very small amounts of toxic alkaloids, to which they believe the symptoms of poisoning produced were due. Their work from a chemical standpoint is excellent, but from a pharmacological point of view seems to be deficient; in fact, Power does not claim to be a pharmacologist. What would seem to be the proper course would have been to test for themselves the action of the plant on various animals and, after deciding which reacted most characteristically, test, after various precipitations, both the precipitates and filtrates on various animals to see whether the original symptoms and pathological lesions could be produced. They failed, however, to test their mother substance. It is well recognized that plants grown under varying conditions and on different soils vary in the amount of the physiologically active principle they contain.
In the case of Crotalaria, Power and Cambier had before them the experiment of Stalker, in which he reproduced the disorder by feeding the plant extract to horses, yet they claimed that the body which they administered was the active principle, merely because it produced some frothing at the mouth and salivation in a kitten. The percentage of active principle they found would be too small to account for the symptoms, except in the case of a very active compound.
Certain of these precipitates were also later examined physiologically by O’Brine.[111] He also found the resin precipitated from an alcoholic extract of the plant and also the alcoholic extract from 2.2 pounds of the dried Astragalus mollissimus to be physiologically inactive.
Oatman,[112] using Power and Cambier’s method with alfalfa (Medicago sativa), obtained a noncrystalline mass which when given in 0.1 gram dose caused frothing at the mouth in a kitten, but no serious symptoms. This 0.1 gram represented about 5 pounds of powdered leaves and tops of the plants.
Since the appearance of Power and Cambier’s work Sayre has published various papers on the loco weeds in the Transactions of the Kansas Academy of Sciences for 1903-4, vol. 19, p. 194, 1905; 1901-2, vol. 18, p. 141; Seventh Biennial Report of the State Board of Agriculture of Kansas, vol. 12, p. 97, 1891; Journal of the Kansas Medical Society, vol. 4, pp. 222 and 241, 1904, etc. He has contributed nothing especially new, but says that “the old theory that an alkaloidal poison is secreted in the plant causing the loco trouble has not been found tenable,” but wishes to be understood that he does not discredit the ground for the opinion that in some mysterious way certain disorders occur in cattle in connection with what is commonly called loco-weed. He suggests that this connection might be somewhat similar to the relationship between the disorder caused by over-feeding half-starved animals on clover or alfalfa[113] and has had the plant analyzed as to its nutritive value, giving the table in the Transactions of the Kansas Academy of Sciences, vol. 19, p. 194. He makes the suggestion that any injurious action the plants may have might be due to the fine, hair-like projections on the plant which mechanically set up irritation. This supposition can be thrown out at once by the experiment of Day and others, who induced symptoms in animals by extracts of the plant, and by the fact that other coarse plants do not act similarly. This fine, hair-like material was found to constitute about 33 per cent of the plant on grinding. But Sayre himself does not seem to be positive as to any conclusion. He, like O’Brine and others, has obtained alkaloidal reactions from the plant, but states he has obtained similar ones from alfalfa.[114] At one time he said:
I do not consider loco directly or indirectly the cause of the condition, but am of the opinion that what is called “locoed” is, first, congestion of the brain and spinal marrow (causing blindness and first symptoms), and, second, softening to a greater or less extent.[115] These terms describing the alleged symptoms of “locoism” might occur in well recognized diseases resulting from brain lesions, which latter occur in so-called forage poisoning and poisoning from foul drinking water, etc.
We are not prepared to affirm or deny that the loco-weed produces a train of symptoms characteristic of the plant.[116]
Again Sayre states:
It seems not unreasonable to suppose that the peculiar condition of the animals of the plains, when they gorge themselves with this highly nitrogenous weed, has something to do with the disease. A condition of malnutrition may set in and give rise to the rapid growth of a toxic-producing micro-organism or an irritating principle. This principle may be capable of cultivation and of producing disease artificially. Be this as it may, we feel warranted in saying that the so-called poison is a development within the animal, not a product preexisting in the weed itself.
Sayre also suggests the possibility of the plants producing hydro-cyanic acid, which, it is well known, occurs in sorghum.[117] In the Journal of the Kansas Medical Society (vol. 4, p. 243), he claims to have isolated a crystalline body, but this he has not tested physiologically. Sayre especially deserves credit for keeping the loco investigation alive, and no doubt his change in position is due to his lack of facilities for pharmacological testing.
Carl Ruedi[118] fed rabbits daily by a stomach tube with 10 c.c. of an extract (unstated strength) of Astragalus mollissimus and recorded the following results:
After only five injections one of the rabbits died, and the post-mortem showed to a nicety the congestion of the whole tract of the vena portæ and the anæmia of the brain. I put six rabbits under the influence of loco, and the effect was marked, but not rapid, if not given in very concentrated solutions. The solutions were prepared differently, and each of the rabbits had its own preparation, but the effect was nearly the same. In the beginning loco acts as a stimulant; the animals get lively, hilarious, running about; cleaning themselves, etc. This lasts about eight hours, then they become very quiet, sit in a corner of a box, and one can do with them pretty nearly what one likes; they do not move from the place, or just run into another corner, to fall back into the same complacent reverie. One can leave the door open and hammer away at the box, but they do not show any inclination to run away. During the excitement, however, they become fierce, and I had once the opportunity to watch one of the drollest things possible: One of the rabbits, two hours after dosing it, got loose and ran under a porch. A heavy tomcat came near this hole, and commenced sniffing about; this offended the rabbit highly, and it jumped on the neck of the cat, bit it through the skin, and the cat ran screaming away. When the animals are first under the influence of moderate doses of loco, they suffer greatly from hyperæsthesia of the cutaneous nerves; when one touches them with a stick while lying in a corner, without hurting them, one sees the platysma working away very forcibly, and sometimes they utter sounds of pain. According to my experiments the loco-weed works slowly but surely; as soon as the anæmia of the brain sets in, the animals act in every respect mad like; one hour they are excitable, and then again dull and languid as can be. The rabbits eat, when well, very quickly, and whenever they have opportunity; not so the locoed rabbit; he eats slowly for a minute or two, then he goes into a corner and meditates, comes forward to nibble at a carrot or a piece of cabbage, but he never eats greedily, and does not steal it from the mouth of his neighbor, or only very exceptionally. I observed these rabbits for ten days; they did not die, because I gave them weaker solutions; but they all became very ill, and as I had to leave the park I killed them with the needle inserted into the medulla oblongata, and made the post-mortem. In all of these cases I found great congestion in the abdomen, and marked anæmia of the brain. The congestion of the vena portæ commences certainly very early, but still the first symptoms are the nervous symptoms, first as excitants, then depressing or sedative, with a marked hyperæsthesia of the cutaneous nerves.
Ruedi made an attempt to isolate the active principle and separated a base, which he calls “locoin,” from an ether shaking. This base, however, he found to be physiologically inactive, but believes the activity to be due to a body which he calls “loco-acid,” which is present in the mother liquid after the shaking with ether. He, however, has not obtained this in any degree of purity and gives no chemical data to substantiate this statement save that the fluid was acid.
Experiments made at the University of Pennsylvania with certain loco plants on cats, dogs, and rabbits proved negative.[119]
Other experiments on rabbits have been made by Doctor Lewis. These rabbits were fed on the leaves, stem, and whole plant, and also extracts of one of the loco plants (presumably Astragalus mollissimus) for one or two months, without producing any noticeable effect.[120]
This uncertainty in the results of the investigation as to the cause of the loco disease turned the attention of observers into other lines. President Ingersoll,[121] of the State Agricultural College of Colorado, in his autopsies on sheep was struck by the presence of tapeworms (Taenia expansa) in the gall duct and small intestines. He apparently tried to prove a relationship between the tapeworms and the locoed condition by feeding the extract of a loco plant to sheep, and thus showing its harmlessness. He prepared a decoction from 20 pounds of loco plant (the species was not stated) and boiled this down from 12 gallons to 1 quart. This concentrated extract was fed in three days to a bottle-fed lamb; this lamb showed no symptoms, although kept under observation for two weeks. This theory of the causation of loco by worms was also considered by Curtice,[122] and later brought forward by Steele[123] and Marshall.[124] This idea is very suggestive when considered in relation to the etiology of bothriocephalous anæmia.[125]
Others, again, have claimed that the disease is due to a parasite found upon the loco plants, but all specimens examined by entomologists proved to be harmless.[126]
Lloyd, from his study of the subject, says:
From first to last I have failed in obtaining a characteristic proximate principle, either from the fresh or dried plant. The disease called loco was as murky as the milk sickness so prevalent in the new settlements of Indiana and Kentucky in early days, and, like the numberless herbs that have been presumed to produce that obscure peculiar disease, milk sickness, loco was unresponsive to my chemistry.[127]
It may be safely said that if a specimen of the plant were to be examined in the ordinary manner by a chemist who had no idea of its importance he would report that it did not contain a characteristic proximate constituent.[128]
Can it be that an admixture of loco and some undetermined plant or earth infected with bacteria taken with the roots, each innocuous under other conditions, can by digestion together in the stomach and intestines result in the production of a poison?[129]
To sum up, it seems to the writer that the poison of loco is a product, and not an educt.[130]
But Lloyd adds, in speaking of the reports of various experts and ranchmen:
Their description concerning its toxic action on animals agreed, and it was folly to argue that so many observers from so many sections of the country could be misled. There must be an undetermined something behind the loco weed.[131]
In 1893 O’Brine, from Colorado, and Mayo, from Kansas, reported on their work with the loco plants. O’Brine failed to isolate any alkaloidal or other poisonous body, and his feeding experiments on himself and on rabbits having failed, he sums up in despair: “The more I examine the loco question, the more I am persuaded that we must look for some other cause besides the loco-weed.”[132] At the end of his report he gives some ash analyses but fails to interpret them. He also fails to give details as to the method of obtaining and estimating his ash. O’Brine’s ash analyses are as follows:
Plant.Total ash. SiO2. Fe2O3 and Al2O3.CaO. MgO.K2O.Na2OH2SO4 Cl.P2O3. CO2.
Astragalus mollissimus (whole plant)12.15 32.77 16.266.05 3.11 13.30 3.21 3.90.476.12 10.55
Aragallus lamberti (whole plant)13.52 17.0812.2114.27 2.6217.265.753.223.873.3017.37
Astragalus caryocarpus12.367.825.9712.10 3.5523.353.385.569.04.6720.62
These analyses are evidently incorrect, as O’Brine estimates a carbon content of 4.13 per cent for the first, and for the second 2.22 per cent, showing incomplete combustion.
Mayo[133] experimented with alcoholic and aqueous extracts of dried Astragalus mollissimus on guinea pigs, with negative results, and was first led to deny a relationship between the disease and the plants. Later, as a result of the post-mortem findings, he was convinced that his first conclusion was wrong and that “the disease is certainly the result of animals feeding upon the loco-weed.” Mayo says:
A careful survey of the experiments performed and observations noted leads me to the opinion that the disease known as “loco” is the result of malnutrition, or a gradual starvation, caused by the animals eating the plants known as “loco weeds,” either Astragalus mollissimus or Aragallus lamberti. If there is a narcotic principle in the plant, chemists have failed to find it and a fluid extract does not possess it, and a ton of the plant eaten by an animal ought to contain enough of the poisonous properties to destroy an animal.
Kobert[134] has also tested the activity of Astragalus mollissimus and says, “Ich fand Astragalus mollissimus ziemlich unwirksam.”
Doctor McEackran[135] fed dried Astragalus mollissimus and Aragallus lamberti mixed with feed to a stabled animal for two months without result. (Animal not stated).[136] Similar negative experiments are reported from the State of Washington, but the amounts used were too small to form any conclusions.[137]
Mr. V. K. Chesnut[138] has busied himself with the loco problem, but mainly in an executive capacity, his own efforts being directed to the study of the relation of the loco plants to the disease on the range. He has done no laboratory work. Chesnut and Wilcox made numerous autopsies on sheep and experiments on animals. They claimed that an extract of Aragallus spicatus produced some slight narcotic action in rabbits. Their pathological examinations failed to show any characteristic lesion, but they state that the cerebral membranes were in all cases slightly congested. They deny any causative relationship to the presence of worms or with feeding upon alkalis. They believe that sheep are more likely to become locoed if not salted regularly. Chesnut describes one case in which a lamb became locoed by nursing from a locoed mother.
In 1901 Reid Hunt, at that time a special agent of the United States Department of Agriculture, studied the loco question in Montana, working mainly with Aragallus spicatus. He moistened the ground-up plant with 93 per cent ethyl alcohol and then percolated it until exhausted. This extract was evaporated and taken up with water so that 1 c.c. of the solution corresponded to 10 grams of the plant. This was fed to an active young rabbit weighing 490 grams, 6 c.c. being fed by the mouth and followed in about an hour by 10 c.c. more, and two hours after this by 15 c.c. This rabbit showed no symptoms during the following day. The next day it was very dull and there was marked muscular weakness, as the rabbit’s legs were spread wide apart and his nose rested on the ground. Later respiration became very slow and the pupils were dilated. The paralytic symptoms increased and finally, after a convulsive movement, the animal died, thirty-six hours after the first feeding. Hunt merely states of the post-mortem examination that the stomach was well filled and that the “walls seem normal.”
Hunt tried to isolate an active principle by the Dragendorff method, but failed to obtain any physiologically active shakings. He tried hypodermic injections of 80 per cent alcohol extractions of the fresh green plant, and after the injection of an extract corresponding to 60 grams of the fresh plant there was no effect produced. He tried to induce symptoms by feeding the plant itself to rabbits, but was unsuccessful, as the rabbits refused to eat the plant. He was not able to induce symptoms with the extracts of the dried plant.[139]
Marshall[140] studied the loco question with regard to sheep and practically denies the existence of a locoed condition due to eating the loco plants, but believes the condition due to bad feeding, parasitism, etc. He lays great stress upon the presence of worms, but fails to see that they may be merely a secondary infection superimposed upon an already morbid condition produced by eating the plants. Others have claimed that the cause is an insect living upon the loco plants. Others, again, have suggested an analogy with trypanosome disorders.
Chesnut has held the view that many of the cases of so-called locoed sheep were really due to parasites, but that there was a true locoed condition due to eating the loco weeds.
The lack of agreement in the results of the investigators has caused many to doubt any positive relation between the plant and the disease, and even as late as 1904 Payne[141] practically says these diseases are due to lack of nutrition and not to the loco plant. The matter has been summed up in a recent work as follows:
Though many chemists have sought for the constituents, none have been able to locate the active properties, the trace of alkaloids, resins, volatile and fixed oils having each in turn been found destitute of it. Yet the poisonous properties are fully established by field observations. The destructiveness of these plants to stock is so great as to have probably caused upward of a million dollars loss in the aggregate, and large bounties have been offered by State governments for an effective method of avoiding such losses. It is considered very probable that the poisonous constituent is albuminoidal.[142]
FOOTNOTES:
NOTES ON VARIOUS MEMBERS OF THE LOCO-WEED FAMILY.
Astragalus caryocarpus is at times eaten in some of the Western States, but is claimed by some at certain stages of its growth to contain a poisonous principle. Frankforter,[143] from experiments on himself, however, denies this.
Astragalus glycophyllus has been used as a diuretic and Astragalus exscapus in the treatment of syphilis.[144] “The seed of A. boeticus, planted in Germany and England, are found to be the very best substitute for coffee yet tried, and so used—roasted, parched, and mixed with coffee.”[145] Astragalus nuttallianus, according to Smith,[146] is a highly nutritious forage plant in spring. Astragalus crassicarpus has been prophesied by him to be a valuable addition to early spring soiling crops. Astragalus adsurgens (nitidus) and one or two other species of Astragalus are still used in Chinese medicine.[147] The Indians of the Southwest are familiar with certain loco plants.[148] The Tewans of Hano are said to eat the root of Aragallus lamberti, and Astragalus mollissimus is applied locally for headaches by some of the Arizona Indians. One of these species is used as a flavoring material by the Coahuillas and is mixed with other plants as spices.[149] Astragalus kentrophyta had a reputation among the Navajos for the treatment of rabies.[150] The use of certain loco plants—Astragalus mollissimus—has been advocated on theoretical grounds in the treatment of certain forms of insanity, but without favorable results.[151] In Peru and Chile Astragalus garbancillo, A. unifultus, and A. ochroleucus have been considered injurious to animals.[152] Astragalus glyciphyllus and A. alpinus have been used in Europe as food for stock.[153]
Details as to the use of other Astragali can be found in Planchon, G., Sur les Astragales, in Journal de Pharmacie et de Chimie, 5th series, vol 24, p. 473, 1891; 5th series, vol. 25, pp. 169, 233, 1892.
FOOTNOTES:
LABORATORY EXPERIMENTS—PHYSIOLOGICAL.
The first point in our investigations was to determine whether the plant exerted any poisonous action and to find some animal which responded regularly to it; then to ascertain if the lack of results of previous investigators was not due to insufficient doses, and later to see if by feeding smaller amounts at repeated intervals symptoms comparable to those described as occurring on the range could not be produced. The animal finally selected was the rabbit.
EXPERIMENTS ON RABBITS.
ACUTE CASES.
Experiment No. 1.—On September 8, 1905, an aqueous extract of 333 grams of fresh Astragalus mollissimus, made in Hugo, Colo., and shipped preserved in chloroform,[154] killed a rabbit weighing 1,616 grams in one hour and thirty-five minutes, while an extract corresponding to 167 grams merely caused drowsiness and loss of appetite in a rabbit weighing 765 grams.
Experiment No. 2.—On November 29, 1905, a rabbit weighing 1,162.3 grams was fed with a concentrated aqueous extract of 500 grams of fresh Astragalus mollissimus, which had been shipped from Hugo, Colo., preserved in chloroform in sealed vessels. This animal died in one hour and ten minutes. The symptoms consisted in dullness, rapid respiration, and signs of pain. At autopsy the stomach and upper part of the small intestines showed hemorrhagic ecchymoses, with dilation of the dural vessels of the brain and cord, with a clot over a portion of the spinal cord.
Experiment No. 3.—On February 13, 1906, a rabbit weighing 992 grams was fed with a concentrated aqueous extract of 500 grams of the fresh Astragalus mollissimus, collected in September and preserved in chloroform water. Before feeding, the rabbit’s ears were warm and the rabbit struggled when any attempt was made to turn him on his back. The temperature at 10.50 a.m., the time of feeding, was 103.5°F.; at 11.15 a.m., 102.5°F. At 11.30 a.m. the rabbit was breathing very rapidly and would stay on his back for some time if placed so. The temperature at this time was 102.6°F. Both pupils, the one exposed to the light and the one protected, were contracted. At 12.02 p.m. convulsive movements of the legs appeared. The rabbit made one leap, the temperature rose to 103.6°F., and after a few convulsive movements of the limbs the anus relaxed and a small stool appeared, the pupils dilated, and the animal died at 12.06 p.m.
Experiment No. 4.—The feeding of the extract of 464 grams induced a fall in temperature of 2.4°F. in three hours, and the rabbit died several hours later (at night).
Experiment No. 5.—March 2, 1906, a rabbit weighing 928 grams was fed with a concentrated extract of 500 grams of the fresh seeds and pods of Astragalus mollissimus, made in September, 1905, and preserved with chloroform water. This animal died in one hour and seven minutes. The animal showed the usual post-mortem conditions.
It was thus found that the aqueous extract of 500 grams of the fresh Astragalus mollissimus would cause death in about one hour in rabbits weighing about 2 pounds (907 grams), these rabbits showing constant clinical symptoms—urination, paralysis, more or less convulsive muscular twitchings, often terminating in general convulsions, drowsiness, and stupor, with more or less anesthesia. The pupils at the time of death were often unequal. At first there was usually a slight rise in temperature, but this was soon succeeded by a fall. Often there were soft stools. The post-mortem lesions in these cases were marked congestion, with hemorrhages in the stomach walls and a secretion of thick mucus. The portions of the stomach walls most affected were the dependent portions near the cardiac end. The intestines showed dilatation of the blood vessels. The mesenteric vessels and also the vessels in the cerebral portions of the dura were markedly dilated; in some cases there were clots, especially at the posterior portion of the brain, between the cerebrum and the cerebellum. At times there were clots over the dorsal portion of the cord. On cutting into the brain the brain substance itself did not appear to be congested. The cord seemed about normal, but the vessels of its membranes were well marked. The other organs showed nothing characteristic macroscopically. These experiments were repeated many times and found to be constant.
These acute symptoms were likewise produced by an extract of 500 grams of the fresh Aragallus lamberti from Arizona preserved in chloroform water (rabbit weighing 1,998 grams). An aqueous extract of 150 grams of the dried Astragalus mollissimus[155] from Imperial, Nebr. (1906), caused death in one hour and fifty-eight minutes in a rabbit weighing 1,530 grams, and an extract of 100 grams killed in one hour and twenty-two minutes a rabbit weighing 736 grams.
An aqueous extract of 100 grams of the dried Astragalus bigelowii induced death in one hour and thirty-eight minutes, the rabbit weighing 1,502 grams.
An aqueous extract of 150 grams of Astragalus nitidus collected at Woodland Park, Colo., in 1906 induced death in three hours and five minutes, the rabbit weighing 1,672 grams.
An aqueous extract of 200 grams of the dried Astragalus bisulcatus caused death after several hours (at night), the rabbit weighing 2,423 grams.
In certain cases this production of acute symptoms was not entirely a question of salt action, as was shown by certain other experiments. In other cases salt action seems to be the important factor, so that the production of these acute symptoms can not always be considered characteristic.
FOOTNOTES:
CHRONIC CASES.
Experiment No. 6.—February 19, 1906, a large gray rabbit weighing 2,055.3 grams was fed with 60 c.c. of fluid representing the concentrated aqueous extract of 250 grams of the fresh Astragalus mollissimus, collected September 18, 1905, and preserved in chloroform. This rabbit was very hard to hold. The ears rested on the body. The temperature at the time of feeding, 1.30 p.m., was 102.3°F. At 2.57 p.m. the animal looked dull but resisted handling. At 3.30 p.m. it urinated. At 4.15 p.m. the temperature was 98.5°F., the pupils were about the same size as before feeding, and the animal became much duller. The next day at 12.50 p.m. the temperature was 102.4°F., and at this time the animal could be handled with greater ease. The animal ate in the morning. The same amount of extract was again fed at 1.24 p.m. At 1.35 p.m. the animal was much duller and could be turned on his back with ease. If disturbed he ran against the wall as if utterly unconscious of the obstruction. The animal had soft, liquid, brown stools and tried to lie down as much as possible. If turned on its back with the feet up it would stay so almost indefinitely. Temperature, 103.8°F.; respiration very rapid. At 2.40 p.m. the temperature was 99.8°F., and the animal died a few minutes later. After death the pupils were much contracted. The vessels of the dura covering the brain were much dilated, but the vessels inside the brain were not dilated. The stomach walls were congested and marked with numerous petechiæ and covered with mucus.
Experiment No. 7.—On February 19, 1906, a white and brown rabbit whose temperature was 103.2°F. was fed 30 c.c. of aqueous fluid representing the concentrated extract of 125 grams of the fresh Astragalus mollissimus, collected September, 1905, and preserved with chloroform. The rabbit weighed 1,502.5 grams. This extract was fed at 1.45 p.m., and at 4.15 p.m. the temperature was 102.6°F., but there were no marked symptoms. The following day at 2.04 p.m. the temperature registered 102.5°F. The same amount of extract was given at 2.09 p.m. The temperature at 4 p.m. was 99.8°F., the animal was dull, and the pupils were perhaps a little smaller. The animal could not be turned over without resistance. The following day, February 21, at 1.30 p.m. the temperature was 102.6°F., and at 1.45 the same amount of extract was given. At 1.54 p.m. the animal was much duller and the breathing was very rapid. At 4.10 p.m. the temperature was 101.3°F. The animal had been dull ever since the feeding was begun. It nibbled food shortly before the last feeding. On February 23 the same amount of extract was given at 2.16 p.m., temperature 99°F. The breathing was very rapid, the ears shaking, and there was a sleepy, dull look about the animal. At 3.30 p.m. the animal was dull, but would still walk about if disturbed. At this time the animal weighed 1,445.8 grams. At 4.30 p.m. the temperature was 102°F. and the pupils were about normal size. There was a marked sleepy look about the animal, which sat quietly in its cage.
February 24, at 1 p.m., the animal was very dull and could with ease be turned on its back with its feet in the air. It would sit in its cage perfectly quiet. The weight at this time was 1,417.5 grams, the temperature 96.6°F. On February 26 the animal weighed 1,360.8 grams. It was dull and refused to eat. The abdomen felt very distended and tympanitic. February 27 the weight was still 1,360.8 grams, and the animal sat in its cage as if asleep, with eyes half closed. There was no diarrhea and the abdomen was very distended. At 11.15 a.m. there was a general convulsion and the animal fell over. At 12 m. the abdomen seemed even more swollen, the animal was hardly able to walk, and it fell over, uttering a cry. Pupils were about normal—perhaps a little smaller. The animal died at 12.10 p.m.
The post-mortem, made immediately after death, showed the abdomen markedly tympanitic, and the large intestines could be outlined through the abdominal walls with ease. The large intestines were of a chocolate color, intensely congested, and marked with hemorrhages. On opening the abdomen there was a decided putrefactive odor, and about an ounce of bloody fluid was found in the peritoneal cavity, together with fibrin flakes. The stomach was pale, the first three inches of the small intestine up to where it turned sharply were pale, and below this the intestines were injected and full of gas and of a dark red color. The kidneys were 3-1/2 centimeters long and were pale, capsules easily peeled off; cortex pale. Liver pale and infected with some coccideæ. The gall bladder was one-quarter inch wide and one inch long. Spleen a trifle pale; lungs pale, nothing abnormal; heart relaxed. On opening the stomach gas and fluid, with some food, exuded. The walls were pale, but pink in some places. There was no marked congestion or hemorrhage or perforation. The mesenteric vessels were dilated. The upper portion of the intestines contained a little mucus-like fluid, but lower down became bloody, and still lower contained pus-like fluid. The walls were hemorrhagic. The large intestine contained a soft, fecal-like fluid, very foul. Its walls were much congested and full of hemorrhagic points. The cortex of the suprarenal bodies was sharply defined, the medullæ brownish. Brain pale, some dural vessels well marked, no clots or hemorrhages. Base of brain pale. No congestion seen on cutting into the brain. Spinal cord showed no hemorrhages or lymph effusions.
Experiment No. 8.—On February 18, 1906, at 2 p.m., a rabbit whose temperature was 102.2°F. was fed with the aqueous extract of 125 grams of fresh Astragalus mollissimus, collected in September, 1905, and preserved in chloroform, 30 c.c. of the fluid being used. At 4.25 p.m. the temperature was 102.4°F. No symptoms were noted. This rabbit weighed 1,644.3 grams. On February 20 at 2.09 p.m. the temperature was 102.2°F. and the rabbit showed no symptoms. The same dose was repeated at 2.15 p.m. At 4 p.m. the temperature was 100.3°F. The rabbit was dull but could not be turned over without a struggle. February 21 at 1.30 p.m. the temperature was 101.4°F. The same amount of extract was fed at 1.45 p.m. At this time the animal was dull and breathed more rapidly. At 4.10 p.m. the temperature was 97.3°F. Next day the same amount of extract was again given at 2 p.m. At 2.16 p.m. the breathing became rapid and the animal duller. The ears were directed forward. At 4.15 p.m. the temperature was 101.6°F.; weight 1,757.7 grams; animal slightly dull. February 24, temperature 102°F., weight 1,786 grams. March 5, weight 1,729.3 grams. The animal was fed at 3.20 p.m. with a concentrated extract of 125 grams of Astragalus mollissimus, collected in September. Temperature at time of feeding 100.4°F.; 3.40 p.m., no symptoms; 4 p.m., temperature 102°F. March 7, weight 1,644.3 grams; March 8, weight 1,672.6 grams; March 10, weight 1,701 grams; March 12, weight 1,658.4 grams; March 14, weight 1,701 grams.
In this case, where the same dose was given in a period of five days, very little effect on the rabbit was noted.
Experiment No. 9.—On March 1, 1906, a black rabbit weighing 2,664.8 grams was fed with a concentrated aqueous extract of 250 grams of fresh Astragalus mollissimus, collected in the fall of 1905.
On March 5 the weight was 2,296.3 grams. The animal was then given the same amount of extract. During the afternoon it passed mucus and thick pieces of feces and was dull; respiration very rapid. March 6, weight 2,282 grams; March 7, 3 p.m., animal very dull and would not eat; sat hunched up, but resisted being disturbed: weight 2,310.5 grams. March 8, weight 2,183 grams; March 9, weight 2,069.5 grams. Pupils dilated; finger could be run almost against the eye, provided the lashes were not touched, without the animal winking or paying any attention. Rabbit ate very little and had not urinated since the preceding day. Left ear had fallen to the side as if the animal were unable to support it. Weight, 1,912.8 grams. From March 9 to March 11, 67 c.c. of cloudy urine were voided. This did not clear with acetic acid. Left eye tearing. March 10, head held to right side. March 12, weight 1,786 grams. Left pupil smaller than right, neither responding to light. Rabbit very weak. March 14, weight 1,729.3 grams. Would not eat. March 16, weight 1,644.3 grams. Right pupil larger than left, neither responding to light. Diarrhea present. Breathing noisy. In sitting down she raised herself on her forelegs, evidently to take the pressure off her abdomen, which was distended. If disturbed, she would butt against the side of the cage, apparently oblivious of its presence. Knee jerks were very active, almost a clonus. Reflex from tendo Achillis active. March 17, forelegs spread out, head falling to left side. The temperature had fallen below 94°F. and would not register on the ordinary clinical thermometer. The ears twitched, the head was thrown back, the abdomen was distended, and the rabbit gritted its teeth. Died. Weight, 1,559.2 grams.
Brain and spinal cord pale. Dural vessels plainly seen but not marked. Intestinal vessels congested. Stomach pale; nothing apparent macroscopically save a small pin-point ulcer.[156] Heart relaxed. Post-mortem examination otherwise negative macroscopically.
Experiment No. 10.—A mouse-colored rabbit weighing 1,927.8 grams was fed February 18, 1906, at 2.26 p.m., with a concentrated aqueous extract of 250 grams of fresh Astragalus mollissimus collected in September, 1905, and preserved in chloroform water. The temperature of this rabbit was 102.6°F. The fluid given was 40 c.c. At 2.45 p.m. the rabbit urinated and at 2.57 p.m. was dull and the respiration became rapid. The animal then aborted and had three young, two of which showed some movement after birth, but were apparently premature.
On February 23 the temperature of this rabbit was 102.9°F. at 1.40 p.m. She was then fed with the same amount of the extract as before. At 2.16 p.m. she lay down and became much duller; left ear fallen to side. At 3.30 p.m. the rabbit was unable to stand. The pupil of the eye exposed to the light was dilated. The animal died without a struggle. The stomach contained much bloody mucus. In the dependent portion of the stomach near the cardiac end were marked petechiæ in the walls, with bright-red blood in the stomach itself. The heart was relaxed. The intestines showed nothing abnormal. The dural vessels of the brain were dilated; there was a clot on the dura over the fourth ventricle. Spinal cord and kidneys normal, the capsules not adhering. Weight, 1,786 grams at death.
Experiment No. 11.—On March 1, 1906, a rabbit weighing 2,126.2 grams was fed with a concentrated aqueous extract of 250 grams of the fresh Aragallus lamberti preserved in chloroform water. On March 5 this dose was repeated, 37.5 c.c. of the fluid being used. March 6 the rabbit weighed 1,956 grams; March 7, 1,913.6 grams; March 8, 1,828.5 grams; March 9, 1,701 grams; March 12, 1,672.6 grams; March 14, 1,644.3 grams.
Experiment No. 12. January 19, 1906, a concentrated aqueous extract of 500 grams of the fresh Aragallus lamberti preserved with chloroform water was fed to a rabbit weighing 785 grams. The temperature at 12.10 p.m., the time of feeding, was 101.6°F. The temperature 1 hour and 43 minutes later was 94.6°F., and the animal died shortly after, showing the same condition as occurred after feeding extracts of Astragalus mollissimus.
FOOTNOTES:
PREGNANT ANIMALS.
Experiment No. 13.—A large, gray, pregnant rabbit weighing 2,891.6 grams was fed on February 22, 1906, with 42 c.c. of fluid, corresponding to the aqueous extract of 250 grams of Astragalus mollissimus collected in September and October, 1905, and preserved with chloroform. At 4 p.m. the animal was dull, but still resisted efforts to handle. On February 24 this animal weighed 2,778.2 grams, and on February 26 it bore a litter of seven young rabbits. One or two of these showed movements of the limbs, but were apparently immature. This rabbit on March 10 weighed 2,537.3 grams; March 12, 2,438 grams; March 14, 2,508.9 grams; March 22, 2,494.7 grams.
Experiment No. 14.—On March 1, 1906, a black rabbit weighing 2,721.6 grams was fed at 12.15 p.m. with a concentrated aqueous extract of 250 grams of the fresh Astragalus mollissimus collected in September, 1905. On March 2 it weighed 2,438 grams; at 2.58 p.m. it still resisted efforts to turn it on its back; at 3.15 p.m. it could be turned on its back with ease. March 6 the weight was 2,338.8 grams; March 7 the animal was very dull, would not eat, pupils dilated, hind legs paralyzed; died during the night; weight, 2,267.9 grams.
The stomach walls were pale save at the dependent portion near the cardiac end, where there was a hemorrhagic, ulcerated area about 1-1/2 by 1-1/2 inches. The intestines were full of gas, but not hemorrhagic. The uterus contained eight immature fœti. The uterine walls were hemorrhagic. The kidneys weighed 9-1/2 grams; their medullæ were dark and the straight tubules well defined. The cerebral dural vessels were congested and the spinal dural vessels were well defined. The bladder was found contracted. The blood gave no bands for methæmoglobin, but showed merely those of oxyhæmoglobin on spectroscopic examination.
Experiment No. 15.—Control experiments made by feeding water were negative, except when a large quantity (150 c.c.) of water was given to a rabbit weighing 1,020.5 grams. The animal died in 12 hours with marked pallor of the tissues (hydræmia), a pathological condition quite different from that obtained by feeding extracts of the loco plants, and no such results were secured with the amount of water used in our feeding experiments, 50 to 70 c.c.
SUBCUTANEOUS INJECTIONS.
Experiment No. 16.—On February 28, 1906, a white rabbit weighing 581.2 grams was injected subcutaneously at 10.35 a.m. with a concentrated aqueous extract of 83 grams of fresh Astragalus mollissimus collected in September, 1905, and preserved with chloroform. The temperature before injection was 102.1°F. At 1.40 p.m. the animal was dull; at 3.12 p.m. the temperature registered 99.8°F. The animal died during the night. The post-mortem examination was negative. Stomach pale; heart relaxed save left ventricle, which seemed contracted; dural vessels of the brain dilated; kidneys perhaps normal. No microscopical examination.
Experiment No. 17.—February 28, 1906, at 10.25 a.m., a guinea pig weighing 496 grams was injected subcutaneously with a concentrated aqueous extract of 83 grams of the fresh Astragalus mollissimus preserved in chloroform water. At 1.40 p.m. there was muscular twitching. The animal was dull and could be easily turned on his back. The hind legs began to show weakness. At 1.50 p.m. the hind legs were almost completely paralyzed and the animal could be easily turned on his back. Muscles of the limbs twitched and semen was expelled. Animal died at 2.15 p.m.
Post-mortem showed dural vessels of cord and brain full of blood. Stomach pinker than normal: mesenteric vessels dilated. Heart almost empty of blood. Kidneys congested.
SUMMARY OF FEEDING EXPERIMENTS ON RABBITS.
These experiments indicate that an acute form of poisoning may be induced by feeding concentrated aqueous extracts of Astragalus mollissimus and Aragallus lamberti from Hugo, Colo., and Imperial, Nebr., to rabbits, and that if the extract is given in smaller and repeated doses a more prolonged or chronic condition may follow.
The rabbits showing the chronic effects of these plants exhibit symptoms which have a marked parallelism with those reported as occurring in larger herbivora (horses and cattle) on the range when locoed; that is, the loss of appetite (Experiment No. 9), the emaciation and loss in weight (Experiment No. 9), the dullness and stupor, with more or less anesthesia (Experiment No. 7), the disturbance in the visual function (Experiment No. 9), and the mental symptoms (Experiment No. 6). The occasional abortion compares with what has been observed in larger animals. The dried Astragalus mollissimus and Aragallus lamberti still retained their poisonous properties, as we were able to kill with aqueous extracts of the dried plants made in the laboratory under the proper conditions.
EXPERIMENTS ON SHEEP.
Experiment No. 1.—On May 31, 1906, a sheep weighing 32.2 kilos was fed with a concentrated aqueous extract of 1,000 grams of the fresh Astragalus mollissimus preserved in chloroform water. The temperature at 11 o’clock, the time of feeding, was 103.4°F. At 11.45 a.m. this dose was repeated. At 12 o’clock the temperature was 104.1°F. At 12.45 the animal urinated. At 1.10 p.m. a similar extract of 2,000 grams was fed. The total liquid used was 1,500 c.c. On June 1 no symptoms were noted. On June 5 an extract of 3,000 grams of fresh Aragallus lamberti and 3,000 grams of Astragalus mollissimus was fed. After feeding this the animal could be easily turned over on its back and its ear pricked with impunity. The animal at this time weighed 30.8 kilos. On June 6, at 11 a.m., the temperature was 104°F. The sheep had numerous soft stools, and was very dull, and would not eat. On June 7 the temperature was 103.7°F. and the sheep still refused to eat. On the 8th the temperature was 103.2°F. at 10.40 a.m., and the stools were still numerous and soft.
There were then fed 640 c.c., representing the aqueous extract of 4,000 grams of the fresh Aragallus lamberti. The animal could be easily turned on its back. It weighed at this time 28.57 kilos. On June 9, at 10.47 a.m., the temperature was 103.4°F. The sheep still did not eat, but had no diarrhea. It now weighed 27.9 kilos, and the temperature was 103°F. at 10.45 a.m.
On June 13 the animal began to eat, and 1,700 c.c. of fluid, representing 5,500 grams of the fresh Aragallus lamberti, were fed. The temperature at 12.30 p.m. was 103°F. On June 14 the temperature was 103.4°F., the animal weighed 28.3 kilos, and refused food. On June 16 the weight was 28.3 kilos; the temperature at 2 p.m. was 103.5°F. There was no diarrhea.
On June 19 the aqueous extract of 1,000 grams of the dried Astragalus mollissimus was fed with 420 c.c. of water. The temperature was 102.6°F. On June 20 the temperature was 102.9°F. at 10.45 a.m.
On June 21 500 c.c., representing the aqueous extract of 1,000 grams of the dried Astragalus mollissimus, were again fed. The animal now weighed 26.9 kilos. On June 26 the animal weighed 26 kilos, and its gait was very uncertain. The temperature was 104.2°F. It was fed 300 c.c. of fluid, representing the extract of 400 grams of the dried Astragalus mollissimus. On June 29 the animal weighed 26.8 kilos and the temperature was 102.8°F. It was fed the extract of 1,000 grams of dried Astragalus mollissimus in 500 c.c. of water. On June 30, at 10.45 a.m., the temperature was 104.2°F. The animal was very dull and died at night.
At autopsy the intestines and stomach merely appeared pale. There were no worms, and the lungs and other organs appeared normal.
Experiment No. 2.—A lamb weighing 15.4 kilos was fed on July 6, at 1.10 p.m., with 640 c.c. of fluid, representing the extract of 2,000 grams of Astragalus mollissimus. At 1.17 p.m. the animal could be turned on its back, and it regained its feet with difficulty. At 1.24 p.m. it urinated and had a stool. The lamb died during the night.
The autopsy the following morning showed the heart filled with clots; lungs normal save for hypostatic congestion. The cerebral and dural vessels were dilated. About 1-1/2 teaspoonfuls of bloody serum were found at the base of the brain. There was none in the lateral ventricles, and no clots. The kidneys exhibited no marked congestion. There was no fluid found in the peritoneal or the pleural or pericardial cavities. The first stomach, however, contained small hemorrhagic spots, and the second was black. There were small hemorrhages in the intestines.
Experiment No. 3.—July 13, 1906, a sheep weighing 19.5 kilos was fed with 640 c.c. of fluid, representing the extract of 2,000 grams of Aragallus lamberti. The temperature at the time of feeding, 1.10 p.m., was 105.3°F. At 1.49 p.m. the sheep could be easily turned on its back. At 2.23 p.m. the temperature was 103.6°F. At 3.42 p.m. the temperature was 103.5°F. At 4.20 p.m. the respiration was fairly rapid. On July 14, at 11.15 a.m., the temperature was 103.6°F. The sheep would run about but could easily be turned over. It had not eaten, but there was diarrhea present. July 15, at 3.30 p.m., the temperature was 104°F. The animal had eaten. On July 17 the temperature was 104°F. and the animal weighed 18.8 kilos. On the 27th it weighed 17.2 kilos; on August 29, 20.8 kilos.
Experiment No. 4.—A lamb weighing 19 kilos was fed August 21, 1906, with 740 c.c., representing the aqueous extract of 2,500 grams of the fresh Astragalus mollissimus, shipped to Washington in September, 1905. This animal ate at night, but the following day was dull. When seen on August 27 there was diarrhea present and the animal was still dull. On the 28th the animal died, weighing 16.7 kilos. There was no autopsy on account of decomposition.
Experiment No. 5.—A lamb weighing 15.6 kilos was fed on September 4, 1906, with an aqueous extract representing 3,500 grams of the dried Aragallus lamberti, 1,000 c.c. of water being used. The temperature at the time of feeding was 104.3°F. At 2.48 p.m. the animal on rising to its feet developed a slight tremor of the fore legs and showed marked disinclination to stand on its feet. The temperature was 104°F. The animal died at 4.25 p.m. The post-mortem was negative, save for some reddening of the second stomach.[157]
These feeding experiments in sheep can not be considered quantitative, because, as is shown later, aqueous extracts of dried plants are often inactive, yet poisonous principles may be obtained from the plants by treatment with digestive fluids.
Extracts of dried loco plants vary much in their toxicity; with some the writer was unable to kill rabbits, even when an extract of 300 grams of the dried plant was used. It is interesting to note that when the field station was established at Hugo, Colo., in 1905, almost all the aqueous extracts of dried specimens sent to Washington would produce the acute symptoms of poisoning in rabbits, but during the third season of its existence many of the samples sent from the same area were much less active, if not inactive.
FOOTNOTES:
LABORATORY EXPERIMENTS—CHEMICAL.
The fact that the aqueous extract of 500 grams of the fresh Astragalus mollissimus, or of 200 grams (in some cases 100 grams) of the dried plant, when fed by mouth, would regularly kill a rabbit weighing about 907 grams, with certain definite clinical symptoms and pathological lesions, was at first arbitrarily selected as our test to aid in the isolation of the active principle. Later the production of chronic symptoms by the aqueous extract or digestion of 200 grams of these dried plants given in doses of 100 grams each on two successive days was considered essential. Carnivora, such as dogs and cats, vomit so easily as to render them unsuitable for these investigations. The aqueous extract was distilled with and without steam, also after acidifying with sulphuric acid, and likewise after the addition of magnesium oxid, but in all cases the distillate was inactive.
The concentrated aqueous extract was shaken by the Dragendorff method with petroleum ether, benzol, chloroform, ether, and amyl alcohol, both in alkaline and acid condition, but the shakings yielded no physiologically active body. Shakings by the Otto-Stas method also proved inactive. Lead acetate, lead subacetate, silver nitrate, mercuric chlorid, alcohol, phosphotungstic acid, trichloracetic acid, ammonium hydrate, sodium carbonate, sodium hydrate, Mayer’s solution, uranyl acetate, silver oxid, and barium carbonate also failed to remove the active constituent. They gave heavy precipitates in all cases, but these proved inactive. Hydrocyanic acid was sought for with negative results. The pathological lesions in the very acute cases suggested in some respects oxalic acid, a saponin, a metal, or perhaps a toxalbumin as the active principle, but none of the precipitants for saponins, such as lead and copper, or the magnesium oxid method yielded a body which was active. Proteids were excluded by the fact that the various proteid precipitants—alcohol, trichloracetic acid, lead subacetate, mercuric sulphate or chlorid, and salting out with ammonium sulphate and sodium chlorid (complete saturation and half saturation)—failed to give an active precipitate. Glucosidal or alkaloidal bodies were also excluded. On dialysing for twenty-four hours, some of the active principle went into the dialysate and some remained in the dialyser. Ether yielded a precipitate from alcoholic solution which failed to kill. The possibility of the activity of the plants being due to its normal acidity was excluded by neutralizing the extract with sodium hydrate and precipitating the salts with alcohol. The filtrate proved active after removing the alcohol.
The negative results in looking for active alkaloidal, or glucosidal, or proteid bodies suggested that perhaps the action was due to some inorganic constituent. The writer then boiled the extract three minutes and as the filtrate was still found active and the proteid precipitate inactive became convinced of the inorganic nature of the active constituents, and finally incinerated the plant. The acid extract from this was also active, but death was delayed several hours. This was believed to be due to the insoluble form into which the compound was converted.[158] In fact, the question of solubility and the avoidance of an acid reaction, which of itself may kill, are the main points to keep in mind.
These experiments indicated that the injurious action toward rabbits of the Astragalus mollissimus and Aragallus lamberti collected at Hugo, Colo., was due to one or more inorganic constituents,[159] but it does not follow that all loco plants have the same poisonous principle nor that the same species occurring on all soils has the same poisonous action.[160]
Of Astragalus mollissimus from Imperial, Nebr., collected in 1906, 200 grams were ashed in a platinum bowl and extracted with water. This aqueous extract when neutralized produced no marked symptoms in a rabbit and the weight of the animal remained about the same.
The ash undissolved after this extraction was then treated with acetic acid and water overnight, and after carefully evaporating off the acetic acid on the bath (tested by litmus paper) the residue was fed, partly in solution and partly suspended in water, to a rabbit weighing 1,800.2 grams. Next day the rabbit weighed 1,771.8 grams, showed paralysis of the limbs, and died during the morning. The stomach was intensely reddened and contracted.
An extract of a similar ash was made by boiling the same amount with a large quantity of 94 per cent alcohol. This was evaporated in vacuo and taken in water and fed to a rabbit weighing 1,459.9 grams. On the sixth day the animal died, having lost 70.9 grams in weight. The stomach showed reddening but no ulcers.
An acetic acid aqueous extract, made from the ash after the alcoholic extraction, proved inactive, showing that the alcohol had removed the active bodies. A 70 per cent alcohol extract of another ashed lot proved active, killing the rabbit overnight.
Of Astragalus mollissimus from Imperial, Nebr., 200 grams were ashed in a platinum bowl and the ash treated with acetic acid water. After freeing from acid, one half of the solution and emulsion was fed one day and the second half fed the following day. The rabbit at the time of feeding weighed 1,275.7 grams. Fourteen days later the animal died, weighing 1,105.6 grams. No autopsy.
A similar extract of the ash from between 100 and 150 grams of the same dried plant produced death in a rabbit weighing 1,190 grams in two hours and fifty-eight minutes.
The acetic acid extract of the ash of 125 grams of a mixture of the dried Astragalus mollissimus and Aragallus lamberti received from Hugo, Colo., June, 1907, after freeing from acid, was fed to a rabbit weighing 1,304 grams on July 29. On July 30 it weighed 1,332.4 grams. August 1 it weighed 1,219 grams, and it died the same day. The stomach was reddened and showed ulcers.
A similar extract from 250 grams of the same dried plants on boiling gave a heavy precipitate, but this precipitate was inactive, while the filtrate killed a rabbit in four hours.
Of dry Aragallus lamberti collected in September, 1906, 200 grams were extracted with water and fed to a rabbit weighing 1,516.7 grams. Two days later the animal weighed 1,360 grams and died the same day.
The ash from 200 grams of the same dried plant was extracted with acetic acid, and after evaporating off the acid this was fed to a rabbit weighing 2,045.3 grams. Seven days later the animal weighed 1,729.3 grams, having lost 316 grams in weight.
The ash from 250 grams of the same species of plant, after similar treatment with acetic acid, induced death in a rabbit weighing 2,069 grams in 2 hours and 20 minutes. The stomach was inflamed.
FOOTNOTES:
EFFECT OF THE AQUEOUS EXTRACT OF ASHED LOCO PLANTS.
The filtrate from the ash from 200 grams of dried Astragalus mollissimus, from Imperial, Nebr., after similar treatment with acetic acid water and freed from free acid, killed a rabbit in several hours.
Hydrochloric acid also rendered the toxic agent of the ash soluble in water, but proved unsuitable for our work, as it was found impossible to obtain neutral residues by mere evaporation on the bath. At first one of the heavy metals or members of the H2S group[161] was suspected, but on passing H2S into the slightly acid extract of the ash no active precipitate resulted, but the filtrate remained active.[162] A special Marsh test was, however, made for arsenic and antimony with negative results. A test for tungsten with zinc and hydrochloric acid proved negative.
Members of the ammonium sulphid group were then suspected, but while ammonium hydrate alone gave a heavy white precipitate, this precipitate, as also the black one with ammonium sulphid, proved inactive save when not thoroughly freed from acid (used for solution). The action of this ammonium sulphid precipitate on rabbits was watched for sixteen days, but without result. Nevertheless, the writer still suspected some of the rare earths.[163]
Sestini[164] had found that if certain plants were nourished with a solution of a beryllium salt, in the ash of these plants could be shown the presence of beryllium.
Two grams of beryllium chlorid were fed in aqueous solution to a rabbit weighing 1,800.2 grams. In four days this animal lost 241 grams and died. The stomach showed the same general pallor seen in chronic locoed rabbits, but no ulcers. The tests for beryllium by Sestini’s method, however, failed to show beryllium in the active loco plants examined.
Thorium chlorid, cerium chlorid, and lanthanum chlorid in 2-gram doses and zirconium chlorid in 3-gram doses produced no chronic symptoms in rabbits or, in fact, any disturbance. Titanium chlorid, 2.5 grams, evaporated in the air and then fed in an emulsion to a rabbit, also proved inactive, but this inactivity may have been due to its insolubility.
Thallium nitrate c. p., in aqueous solution, in 2-gram doses, killed a rabbit weighing 2,154.6 grams in two hours and fifteen minutes. The stomach in this case, while pink, was not hemorrhagic.
Zirconium chlorid has an astringent taste, and if fed repeatedly will cause the metallic astringent action. On boiling an acetic acid solution of the ash with sodium acetate a precipitate formed.[165]
The presence of zirconium was thus suspected and Dr. E. C. Sullivan, of the United States Geological Survey, estimated it to be present in the ash of a sample of Aragallus lamberti in about 0.01 per cent zirconium oxid, with also 0.1 per cent titanium dioxid.[166]
Zirconium chlorid, 3 grams, was fed in aqueous solution to a rabbit weighing 850.5 grams. This rabbit lost 96 grams in seven days, and was then fed 3 grams more of the same solution and the following day 2 grams more. It died eight days later, weighing 656 grams. The stomach and intestines were contracted, but showed no ulcers. However, 4 grams killed a rabbit in two hours and thirty-two minutes.